6: Một vật chuyển động thẳng biến đổi đều theo phương trình x = 400 + 10 – 2 + t2 (x: m;
t: s). Xác định
a/ tọa độ ban đầu, vận tốc ban đầu.
b/ gia tốc của chuyển động.
c/ quãng đường vật đi được sau khoảng thời gian t = 20 s.

An insulated thermos contains 148 g of water at 72.7 ˚c. you put in a 11.7 g ice cube at 0.00 ˚c to form a system of ice + original water. the specific heat of liquid water is 4190 j/kg•k; and the heat of fusion of water is 333 kj/kg. what is the net entropy change of the system from then until the system reaches the final (equilibrium) temperature?

An air-filled capacitor is formed from two long conducting cylindrical shells that are coaxial and have radii of 26 mm and 103 mm. the electric potential of the inner conductor with respect to the outer conductor is - 700 v (k = 1/4πε 0 = 8.99 × 109 n · m2/c2) the energy stored in a 1.0-m length of this capacitor is closest to

Which of the following is a measure of the amount of light a star directly emits?               a.  luminosity    b.  intensity    c.  wavelength    d.  brightness